Reducing agent treatment of crosslinked cellulosic textiles having a ketone group in the cross-link



FIFSSU? United. States Patent 6 ice ABSTRACT OF THE DISCLOSURE Treatment of cellulosic materials containing carbonyl radicals with a reducing agent to improve resistance of said material to hydrolysis in either an alkaline or acid medium.

This invention relates to a method for further modifying cellulosic materials containing carbonyl t'adicals and also relates to {he cellulosic materials so modified. In particular, the invention relates to a method for treating cellulosic materials containing carbonyl radicals with a reducing agent.

In the growing field of technology concerned with chemical modifi'catio'ii of cellulosic materials and especially textile forms such as yarn or fabric compiiising cellulosic fibers, there have been substantial advances iii the direction of ififtroducing functional groupsfj, which, in turn, have a marked effect on the physical and chemical properties of thjcellulosic materials. One area of intensive study in this field relates to chemical modification of cellulosic textiles to impart crease-resistant and shape retentive properties. Another avenue of approach involves the introduction of polar radicals in order tdjimpart additional desirable reactivity to the cellulose polymers.

(Jo-pending application Ser. No. 404,525; filed Oct. 16. 1964, now abandoned, entitled Process for Modifying Polymeric Materials and Modifier Reactairts for Such Use, discloses the use of unique reactants for use in modifying cellulosic materials, among others. ne class of the reactants described in the afore-mentiolned application are ketones which react wi h the cellulose, thereby introducing carbonyl radicals. Di-functional ketone reactants having appropriate molecular structure are utilized to improve the crease recovery of cellulosic textile fabrics.

in addition to the foregoing, US. Patent No. 2,711,971 and US. Patent No. 3,109,695 describe methods of treating cellulosic textile fabrics to introduce carbonyl radicals into the cellulose polymer. British Patent No. 959,522 describes a process in which a cellulosic textile fabric is treated to introduce acrolein, a carbonyl radical containing substance.

In general, cellulosic materials modified by the introduction of carbonyl radicals by reaction of suitable car bonyl compounds with cellulosic polymers exhibit limited stability when exposed to various chemical substances of even moderate activity. For example, a white cotton textile fabric, modified by introduction of carbonyl radicals to impart wrinkle-resistance, becomes yellowed or discolored when subjected to repeated launderings. Such discoloration is due to the effect of exposure to alkaline conditions. It is obvious that such discoloration represents a severe disadvantage to the utility of carbonyl-containing chemicals which could otherwise be used for imparting wrinkle-resistance to cotton or cellulosic fabrics.

In addition to the above, cellulosic materials contain- Patented Mar. 3, 1970 ing car-bonyl radicals have poor resis ance to hydrolysis in either acid or alkylinmedia. Thus, the improved properties obtainable as a result of the treatment of cellulosic materials with carbonyl-containing substances are not truly permanent in the sense that exposure of the cellulosic mategial to hydrolytic conditions may result in loss of properties due to loss of the carbonyl-containing substances or toother chemical changes.

In viewof the foregoing, it is an object of the present inventiorrto improve tlie stability of cellulosic materials which have been modified by introduction of carbonylcontaining substances.

It is a -fi1r ther object ,of this invention to improve the stability of cellulosic materials which have been modified by the introduction of T carbonyl-containing radicals, by treatment thereof with al'reducin-g agent.

It is another object of the present invention to stabilize cellulosic materials containing carbonyl radicals by treatment with reducing agents so that the cellulosic polymers are substantially unafiected by exposure to hydrolytic conditions' Anoher object of the present invention is to substantially eliminate discoloration by laundering of cellulosic materials which have been treated to introduce car-bonylcontaining substances.

Briefly stated, one embodiment of the present invention is a method of treating a cellulosic material containing carbonyl radicals whiclncomprises the step of treating the said cellulosic material with a reducing agent having sufficient reducing power to convert at least a substantial portion of the carbonyl radicals to a reduced form.

As indicated above, there are many prior art processes invloving treatment ofj cellulose or cellulose-containing materials with carbonyl'gcontaining substances in order to impart improved properties. The present invention is intended to encompass ali'isuch modified cellulosic material regar'dles s of the na ure of the carbonyl-containing substance andthe specific 'manner of introduction thereof. In addition, the present invention does not distinguish between materials formedexclusively from cellulose, such as a cotton fabric, and those which contain cellulosic polymers in addition to others. The latter class includes, gor example, a fabric oomposed of cotton and polyester hers.

Since carbonyl radicals are not easily reduced, it is necessary to choose reilucing agents which have substantially strong reducing power. The alkali borohydrides are typical of the preferred reducing agents suitable for use in the present invention. This class of materials includes sodium borohydride (NaBH potassium borohydride (KBH and lithium borohydride (LiBI-I Application of the reducing agent to the carbonylcontaining cellulosic material can be accomplished by any convenient method. Thus, the cellulosic material can be immersed in a solution containing the reducing agent or, alternatively, the cellulosic material may be padded or sprayed with a solution containing the reducing agent. Al though any inert solvent may be utilized to prepare the solution containing the reducing agent, aqueous solutions are preferred because of the simplicity of the operation and from the stand-point of cost.

As is well known, the solubility and reactivity of reducing agents may be dependent on the pH of the environment. (See Melliand Textilber, 44, August 1963, pp. 839-843.) Certain reducing agents such as the alkali borohydrides are more effective at a relatively high pH, of the order of 10 or more; whereas others such as morpholine borane are preferably utilized at a relatively The reduction of carbonyl radicals with alkali borohydrides can be implemented by the use of certain inorganic salts which act as catalysts or accelerators. This phenomenon is disclosed in U.S. 3,118,724. Such catalysts or accelerators include complex""'metal salts of copper, nickel and colbalt, and magnesium, aluminum and lithium halides.

The effect of treatment of carbonyl-containing cellulosic materials in accordance with the present invention can be analytically determined by analysis of the change in carlgpnyl content. From a practical stand-point, the improvement obtained by treatment in accordance with the present invention may be obtained by results of tests such as the following: I

' (l) Decrease in the weight loss resulting from exposure to hydrolytic conditions.

(2) Absence of discoloration after exposure to conditions which would otherwise cause discoloration.

(3) Improved stability to hydrolytic conditions determined from measurement of physical properties.

Set forth below are examples-lwhich are intended to illustrate the process of the present invention. As can be se' en, the cellulosic materials, following treatment, are superior to the control samples.

The standard tests utilized in the following examples are referenced as set forth below:

(1) Carbonyl content: (A) ,H. Stiibchen-Kirchner, fpesterr. Chem. Z. 61 132 (1960); (B) U. Strle, 1. -'Eucepa Symposium Darmstadt,' ;195 8 (2) Crease recovery: ASTM-DI 2 95-60T Reflectance: ASTM-E97-5S (green, tristumulu filter) EXAMPLE. 1

Samples of 80 x 80 cotton print cloth were modified with his (Z-pyridinium ethyl) ketone dichloride according to the following procedure.

The cloth was impregnated with an aqueous solution of the ketone dichloride using a laboratory padder. The cloth was then framed and dried Lat 60 0., treated with an aqueous sodium hydroxide solution, .saturated.with sodium chloride and maintained in a flat condition-for about one minute. The cloth was then rinsed-successively with dilute acetic acid, water acetone and finally washed thoroughly in a dilute non-ionic detergent solution. The cloth was then framed and dried.

hydride solution was varied as indicated in the table below.

A control sample of the ketone dichloride modified cloth was analyzed and was found to have a weight gain of 4.75% and a carbonyl radical content of 0.92 weight percent.

Set forth below in tabular form are the results of this experiment, showing the percent carbonyl content and the crease recovery of the various samples.

Crease recovery (degrees Wet Percent Percent decrease in 00 Duration of content 5 reduction content Dry None minutes... minutes It may be seen that the crease recovery properties of the ketone modified cloth are not affected by the reduction of'the carbonyl radical content.

Samples A through F were exposed to alkaline hydrolytic conditions by immersion in a 0.5 N sodium hydroxide solution for a period of about 3 hours. The alkaline solution was maintained at about C. and a fabric-liquid weight-"ratio of about 1 to 50 was used. Sample A lost a significant proportion of the increase in weight attributable to the ketone dichloride treatment. In addition, sample A took on a yellow color and exhibited a loss in crease "recovery.

For samples B and C, the extent of the discoloration, loss in weight and loss in crease recovery represented an improvement over sample A.

Samples D, E and F remained white in color, lost substantially no weight and showed substantially no decrease in crease recovery.

EXAMPLE 2 Samples of the cloth, modifiedas above, were treated with a reducing agent in the following manner. The samples were immersed in a solution of 0.3% by weight sodium borohydride in isgprgpanol solution, the solution being maintained at a tempgrature of about 50 C. The su at e 9t P89F= of the samp s 9 the odi m bo e- EXAMPLE 3 Samples of x 80 cotton print cloth were modified with di-hydroxy acetone in accordance with the general procedure described in U.S. 3,109,695. The samples were found by analysis to have exhibited a weight gain of 9.2% 5 a d h t a Qarbonyl radical content of 1.5 Weight percent,

Samples as described above were treated with sodium borohydride by immersion in a solution thereof. The fabric to solution ratio was 1 to 50. The specific conditions of each of the experimental runs was as follows.

The samples were treated with the respective solutions using a laboratory padder. Following impregnation of the samples, they were exposed to super-heater; steam at a temperature in the range of from about l-ll0 C. in

Dimethyl fqrihamide The samples tested in gpcordance with runs 3 and 4 exhibited relatively high resistance to both acid and alkaline hydrolytic conditions.

EXAMPLE 4 Samples of 80 x 80 cotton print cloth were inodifid with acetone-formaldehyde precondensate in accordance with the general procedufe in US. 2,711,971. 'Ifhe sal'm ples were found by analysis to have a weight gain of 10.2% and a carbonyl content of 1.1%.

Samples modified as above, were immersed in an aqueous solution containing 5% sodium borohydfide and 0.02% K Ni(CN) Thejsolution contained sodium hydroxide in an amount to provide the 0.2 N solution. The fabric to solution ratio was 1 to 50. The solutions were maintained at 65 C. Y

Set forth below are the results of these experiments:

a laboratory steamer for a period of about 5 minutes. The steamed samples were rinsed in succession with 1% acetic acid solution, water and were then washed thoroughly in non-ionic detergent solution, niaintained at 50 C. The samples were framed and dried." The following results were obtained:

Reducing solution: Percent CO -None 1. Solution A 0.3 Solution B 0.31

The unreduced and the reduced samples were exposed to alkaline hydrolysis (2 N NiaOH at the reflux temperature' for 3 hours, fabric-solution ratio 1 to. 5, 0), and the following changes were noted as a result of the reducing treatment:

0 Percent w gg decrease Loss 01 Reduction Percent oi C0 Before Alter reflectance time, hours content 30 Sample hydrolysis hydrolysis percent Sample Not reduced 215 ,190 13 A N011? g e zg lgoha 225 218 2 3 20 82 rea w/ o 220 209 1 6 0.18 84 EXAMPLE 6 After reduction, the samples were exposed to alkaline hydrolysis by treating with a 1 N aqueous NaOHsolution for 3 hours at 65 C. (fabric to solution ratio of 1,,to 50). After hydrolysis, the following results were obtained:

Crease Recovery Loss of Before After ance after Percen t ioss oi Hydrolysis hydrolwt. gain in ysis, hydrolysis Dry Wet Dry Wet percent It is apparent that unreduced sample A was discolored (as shown by the loss of reflectance), and lost resilience (as shown by the loss in crease recovery) while the reduced samples B, C and D were unchanged after the hydrolytic treatment.

EXAMPLE 5 contain 5.0 weight percent of sodium borohydride and sufficient sodium hydroxide to provide a 0.2 N concentration. A second aqueous solution, solution B, was made up to contain the same amount of sodium hydroxide and sodium borohydride as solution A and contained, in addition, 0.2% K,Ni cN Samples of x 80 cotton print cloth were modified with acetone formaldehyde precondensate irifaceordance with Example 4 of US. 2,711,971. One group of samples, designated Sample A, was found by analysis to have a weight gain of 15.4% and a carbonyl content of 1.5%. Another group of samples, designated Sarriple B, was found by analysis to have a weight gain of 10.2% and a carbonyl content of 1.1%.

Samples as described above were immersed in an aqueous solution of morpholine borane of 5 weight percent. Sufficient sulfuric acid was added to the solution to give a pH of about 1.5. The solution was maintained at a temperature of about 60 (It; and the samples were immersed for about 5 hours, the fabric to solution ratio being 1 to 50.

Set forth below are the results:

Percent C0 Percent Percent Reduction decrease loss 0! Percent oi 00 added wt. gain Before After content weight Sample A 15. 4 l. 5 0. 8 47 3 B 10. 2 l. 1 0. 7 36 5 It can be seen that a substantial reduction in carbonyl content can be obtained without significant overall weight loss,

EXAMPLE 7 Samples, treated as above, were impregnated with an aqueous soldtion containing 1% by weight of sodium borohydride :and sufiicient sodium hydroxide to provide a concentration of 0.2 N. The impregnation was accomplished by use of a laboratory padder. One set of samples, SampleflA, was exposed (to super-heated steam at a temperature "of 100-110 Cffor a period of two rhinutes in a laboratory steamer. Another set of samples, Sample B, was dried in a laboratory forced air oven at a temperature er 95 C. for a period of about 5 minutes.

Both sets of samples were successively rinsed with 1% acetic acid solution and water and were then thoroughly washed in a'non-ionic detergent solution, maintained at a temperature of 50 C. The samples were then framed and dried. The results of this experiment were as follows:

Percent decrease Tensile (W) Tear (W) Percent of-CO r atter 10 Sample content lannderings launderlngs Not reduced 1. l 35 1. 1

1 Tested according to strip method, "ASTMD-39-59. 2 Tested according to Elmendorf method, ASTM-D-14Z4-59.

All of the above samples were then exposed to alkaline hydrolytic conditions, i.e., an aqueous 2 N sodium hydroxide solution, for a period of three hours at atemperature of about 100 C. Set forth below are the values of crease resistance and reflectance, measured both before and after exposure of the samples to hydrolytic conditions.

Crease Resistance pry (W+F) Reflectance Sample Before After Before After Not reduced 268 207 87 71 Reduced A. 243 223 86 81 Reduced B 248 285 87 E0 Morpholine borane, the use of which is described in one of theexarnples above, is typical of the group of amino boranes which are generally suitable as reducing agents in the present invention. The formula for amino boranes is as follows:

In general, reducing agents which can be used for practicing the process of the present invention are those having an value lower than about +1, r value being defined as the negative logarithm of the equilibrium hydrogen pre ssure over the solution of reducing agent (see Melliaiid Textilber 44, p. 839, 1963). I

The concentration of reducing agent required to obtain the desired result is dependent upon the carbonyl content of the cellulosic material to be treated and is also dependent upon the activity of the particular reducing g nt selected. I g nera concentrations in the range of about 0.5% to 5% by weight in the treating solution are effective.

Of-course, the usual reaction parameters which affect reducing reactions also apply'in the present invention. Thhs, for example, the temperature utilized must be considered, although temperatures in the wide range up to C. give satisfactory results.

The present invention has been shown to substantiallv increase the utility of cellulosic materials which have previously been treated to introduce carbonyl radicals. In general, the carbonyl content of the cellulosic material isof little consequenceand likewise, the manner in which the carbonyl radical is introduced in the cellulosic material is of minor importance. The process of the present invention is -applicable regardless of Whether the cellulosic materials are side chain modified or whether they are cross-linked. It is immaterial whether the cellulosic materials have been reacted with carbonyl containing radicals in the presence of alkaline or acidic catalysts or whether reacted in the presence of swelling agents or in their absence.

The cellulosic materials which are suitable for treatment in accordance withthe present invention may be composed wholly or in part of natural cellulose such as cotton, and regenerated cellulose such as rayon or cellophane film. The cellulosic materials may also include linen, flax and the like.

The physical shape and character of the cellulosic materials which are amenable to treatment by the present invention include such well known forms as film, fiber, yarn and fabric.

What has been described above is a process for modifying the characteristics of cellulosic materials which have been previously treated to incorporate carbonyl radic'alsl It has been shown by use of examples that the treatment of the present invention which involves use of a reducing agent stabilizes the cellulosic materials in question and eliminates certain undesirable properties. It is to understood that the examples are merely illustrative and changes in the process as described may be made by one skilled in the art.

What'is claimed is:

1.3m method of treating a crosslinked cellulosic textile material containing "dimethylene ketone or die'thylena ketone crosslinks which comprises treating said crosslinked textile material with a solution comprising a reducing agent having a r value below about +1, r being defined as the negative logarithm of the equilibrium hydrogen pressure over the solution of the reducing agent.

2L"The method of treating a crosslinked cellulosic textile material containing 'dimethylene ketone or diethylene ketone crosslinks which comprises treating said crosslinked textile material with a solution comprising an alkali borohydride as a reducing agent.

3. The method of claim 2 wherein said reducing agent is sodium borohydride.

4. The method of treating a crosslinked cellulosic textile material containing dimethylene ketone or diethylne ketone crosslinks which comprises treating said crosslinked textile material witha solution comprising an amino borane.

5. The method of claim 4 is morpholino borane.

6. The method of treating a cellulosic textile material which has been crosslinked with a formaldehyde-acetone condensation product having up to 4 methylol groups per mol of Zicetone which comprises treating said crosslinked textile iiraterial with a solution comprising a reducing agent hfiving a r value below about +1, r being defined as the negative logarithm of the equilibrium hydrogen pressure over the solution of the reducing agent.

7. The method according to claim 6 wherein said reducing' agent is an alkali borohydride.

8. The method of claim 7 wherein said reducing agent is sodium borohydride.

wherein said reducing agent 9 l0 9. The method according to claim 6 wherein said FOREIGN PATENTS reducing agent is an amino borane.

10. The method of claim 9 wherein said reducing 610655 12/1960 Canada" agent is morpholino borane. ER REFERENCES 0 5 Meller, TAPPI, vol. 36, No. 8, pp. 366-367 (1953). References Meller, TAPPI, vol. 38, No. 11, pp. 682-6 87 1955 UNITED STATES PATENTS Nevell et al., Journal of the Textile Institute, v01. 53, 2,898,333 8/1959 Jullander 3 s 107 X 962% 017,316 1 1962 R 8108.5 1032548 41962 3 223 8 107 10 GEORGE F. LEMES, Pnmary Exammer 3,043,719 7/1962 Burr et a1. 8-4163 X J. CANNON, Assistant EXamillel' 3,198,651 '8/1965 Shiraishi 8108 X 3,318,657 5/1967 Wade m 8 -107 X US. Cl. X.R.

3,341,279 9/1967 Fregermuth et all "N 8-116 X 15 ,407 2 23 UNITED STATES PATENT OFFICE PO-1D50 5 9 CERTIFICATE OF CORRECTION Patent No. B A-98,73 Dated March 3, 1970 Inventor(s) Giuliena. C. Tesoro It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Column 2, line 2, "alkyline" should read -*-elka.line--.

Column 3, line 14, "colbalt" should read --cobelt--; line '40, "tristimulu" should read --tristlmulus--. Column 4, lines C 60-65, in the table line (2), "NeOh" should read --Ns0H--. Column 6, line 51, 'perecnt" should read --percent--; line 60, in the table, the caption for the third and fourth columns should read:

Percent C0 Before Iiter Reduction Column 7, line 22, in the table, second column, "1.1 4" should read "0.1 4".

SIGNED AND SEALED 'SEP z e 1970 Eam-annmh m m Attosting Offioor Oomgnam of PstLnts 

